JP2011007474A - Sprinkler type latent heat recovery heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower a temperature of high-temperature exhaust gas within a limit of the heat resistance of a latent heat recovery heat exchanger formed of titanium without using a heat exchanger for a high temperature while effectively utilizing the sensible heat of the high-temperature exhaust gas.SOLUTION: The high-temperature exhaust gas is sprinkled at an inlet side or an outlet side of the latent heat recovery heat exchanger, the sprinkled water is heated by the heat of the exhaust gas to be water vapor, and the gas temperature is lowered. The water vapor generated by sprinkling water is condensed together with the original water vapor of the exhaust gas by taking advantage of characteristics of a latent heat recovery device. The increased condensation latent heat is also utilized for water supply to a boiler, for example, as high-temperature water.

Description

  The present invention is a heat which recovers the generated steam and the latent heat of exhaust gas by directly cooling the sensible heat of flue flue gas by water spray for energy saving of boilers, heating furnaces and other devices that burn fossil fuels. Regarding the exchanger.

  The current combustion exhaust gas such as boilers is released to the atmosphere at a temperature of several hundred degrees from the chimney, but this is released while the latent heat of condensation held by water vapor is included. It is considered the last remaining energy-saving measure for oil-fired combustion equipment.

As a means for realizing this, a heat exchanger has been devised in which exhaust gas is cooled to the dew point temperature or lower with cold water using a heat exchanger and the latent heat of the exhaust gas is recovered as hot water. (See Non-Patent Document 1)
When cooling below the dew point temperature of exhaust gas, acidic condensate is generated and corrosion occurs in the heat exchanger, so titanium is used as the heat exchanger material. (See Non-Patent Document 2)

In addition, the method of sprinkling the exhaust gas is also used in exhaust gas desulfurization equipment, etc., but means such as reheating and releasing the exhaust gas that has come out of the desulfurization equipment is taken for the purpose of cooling effect. Is not a technology.
Energy Conservation Center Foundation, 2000 Eleventh Energy Conservation Grand Prize 21st Century Energy Conservation Equipment / System Award Winning Equipment Overview, page 7 Takaharu Ozawa; “Unit heat exchanger made of titanium that can recover latent heat from commercial gas-fired boilers, etc.” Titanium, vol. 54, no. 2, 16 (2006)

  Since this latent heat recovery heat exchanger aims at recovering the latent heat of exhaust gas, the material constituting the heat exchanger uses titanium in consideration of corrosion resistance, and the heat resistant temperature is considered to be limited to about 400 ° C. The inlet temperature of the exhaust gas is limited to a relatively low temperature.

  However, there are many demands for treating exhaust gas at higher temperature in the actual usage environment. Moreover, conventionally, the high-temperature sensible heat part of the exhaust gas is recovered using a high-temperature heat exchanger, and the latent heat part is further recovered from the low-temperature exhaust gas, but the high-temperature side heat exchanger is not used. In addition, while trying to lower the temperature of the exhaust gas to within the heat resistance limit of the titanium latent heat recovery heat exchanger, the sensible heat of the high temperature exhaust gas is also effectively utilized.

  Latent heat recovery heat exchange to absorb the sensible heat of the high-temperature exhaust gas discharged from the chimney of a combustion apparatus such as a boiler and the latent heat of water vapor contained in the exhaust gas into the water through the heat exchanger tube and utilize the generated hot water In the cooler, a watering device for cooling is provided on the exhaust gas inlet side of the latent heat recovery heat exchanger provided in the flue to sprinkle the exhaust gas.

  Sprinkling and exhaust gas exchange heat by direct contact, cooling the high temperature exhaust gas to 400 ° C or less and passing the generated water vapor together with the exhaust gas through the latent heat recovery heat exchanger, and the latent heat of the newly generated water vapor together with the latent heat of water vapor in the exhaust gas to recover.

Sprinkling may be performed from the exhaust gas outlet side.

  In the present invention, water is sprayed into the high temperature exhaust gas at the entrance side of the latent heat recovery heat exchanger without the heat exchanger on the high temperature side, so that the sprinkled water is heated by the heat of the exhaust gas to become water vapor, and the gas temperature is lowered. For this reason, the heat exchanger is protected from high temperature, and the water vapor generated from the water spray is condensed with the original water vapor of the exhaust gas by utilizing the features of the latent heat recovery device. It can be used.

  In this way, the latent heat recovery heat exchanger can be used for high-temperature exhaust gas, and the application can be expanded, and even if acidic condensate is generated in the region below the dew point temperature of the latent heat recovery heat exchanger. Since it is diluted by watering, the usable range is widened even for highly corrosive exhaust gas.

  An embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the water spray type latent heat recovery heat exchanger of the present invention is formed by stacking and integrating a plurality of the heat exchange units 2 of FIG. 2, and using both ends of the casing 11 as an exhaust gas inlet 6 and an outlet 7. On the inlet side of the exhaust gas at the top of the latent heat recovery heat exchanger 1, a sprinkler 3 for cooling the high temperature exhaust gas is provided.

  As shown in FIG. 2, the heat exchanging unit 2 forms a water flow path with a spiral coil 10 in which a titanium corrugated tube is spirally wound around a flat plate, and the water flow path is accommodated in a cylindrical casing 11. Both pipe ends pass through the casing wall and are taken out of the casing to form a water supply inlet 4 and an outlet 5.

  When high-temperature exhaust gas to be discharged to the chimney of a combustion apparatus such as a boiler is passed through this latent heat recovery heat exchanger and water is sprayed so that the high-temperature exhaust gas is cooled to 400 ° C. or lower, Evaporates into water vapor, but the generated water vapor passes through the latent heat recovery heat exchanger together with the exhaust gas, and the latent heat of the newly generated water vapor is recovered along with the water vapor latent heat in the exhaust gas.

  When the exhaust gas exit side is at the upper part of the heat exchanger, the operation is carried out under watering conditions such that the cooling effect reaches the gas inlet side even if the water sprinkling is performed from the upper exhaust gas outlet side.

The Example which installed the watering apparatus is shown in FIG. When an exhaust gas having a temperature of 800 ° C. and a flow rate of 3000 Nm ³ / hour was flown from the entrance side of the upper part of the heat exchanger and watering of 20 liter / hour was performed on the exhaust gas flow, the exhaust gas inlet temperature was lowered to 400 ° C. or less. At the same time, the heat gain of about 10,000 kilocalories was obtained by the latent heat recovery.

Schematic of the latent heat recovery heat exchanger equipped with the watering device of the present invention Heat exchange unit as a component of latent heat recovery heat exchanger

1 latent heat recovery heat exchanger 2 heat exchange unit 3 water sprinkler 4 water supply inlet 5 water supply outlet 6 exhaust gas inlet 7 exhaust gas outlet 8 drain valve 9 frame 10 corrugated tube spiral coil 11 casing 12 fixed frame

Claims (1)

  A water flow path is formed with a coil of a titanium corrugated tube spirally wound on a flat plate, which is housed in a cylindrical casing, and both ends of the coil penetrate through the casing wall to the outside of the casing to supply water. The unit used as the inlet and outlet is a unit heat exchange unit, and multiple units are stacked and integrated, and the exhaust gas inlet and outlet sides are connected to the exhaust gas inlet and outlet using the ends of the casing. Latent heat recovery heat exchanger with sprinkler for cooling high temperature exhaust gas

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